Unit 1 - Topic 2 - Proteins - Section C - Protein structure, ligand binding and conformational change - Part II - Ligand binding changes the conformation of a protein Flashcards
What is a ligand
A substance that can bind to a protein
What can allow binding to ligands
R groups not involved in protein folding
What do binding sites have
Complementary shape and chemistry to the ligand
What happens as a ligand binds to a protein-binding site
The conformation of the protein changes
What does conformation change do to a protein
Causes a functional change in the protein
Where do allosteric interactions occur
Between spatially distinct sites
What does the binding of a substrate molecule to one active site of an allosteric enzyme increase and why is this important
Increases the affinity of the other active sites for binding of subsequent substrate molecules. This is of biological importance because the activity of allosteric enzymes can vary greatly with small changes in substrate concentration.
What do many allosteric proteins consist of
Multiple subunits (have quaternary structure
Allosteric proteins with multiple subunits
show what
Co-operativity in binding, in which changes in binding at one subunit alter the affinity of the remaining subunits
Allosteric enzymes contain a second type of
site called what
Allosteric site
What do modulators do
Regulate the activity of the enzyme when they bind to the allosteric site
What follows the binding of a modulator
The conformation of the enzyme changes and this alters the affinity of the active site for the substrate
How do positive and negative modulators affect enzyme activity
Positive modulators increase the enzyme’s affinity for the substrate, whereas negative modulators reduce the enzyme’s affinity
The binding and release of oxygen in haemoglobin shows what
Co-operativity
How does oxygen show co-operativity
Changes in binding of oxygen at one subunit alter the affinity of the remaining subunits for oxygen.
